A nodal diagnosis by computed tomography is unreliable for patients who need additional gastrectomy after endoscopic submucosal dissection.

PURPOSE: T1 gastric cancer is treated by endoscopic submucosal dissection (ESD) or surgery, considering the risk of lymph node metastasis. Additional gastrectomy is necessary when the pathological specimens after ESD show some risk of lymph node metastasis. Preoperative computed tomography (CT) after ESD sometimes reveals enlarged lymph nodes, which should prompt surgeons to select D2 over D1/D1+. However, whether or not CT after ESD is reliable remains unclear.

METHODS: Patients who underwent radical gastrectomy for clinical T1 between April 2015 and June 2019 were enrolled. The patients were classified into those who underwent CT after ESD (group A) and those who underwent CT before primary surgery or ESD (group B). The accuracy of the nodal diagnosis was compared between groups.

RESULTS: A total of 650 patients (group A; 81, group B; 569) were examined. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value (group A vs. group B) were 77.8% vs. 84.2%, 0.0% vs. 15.9%, 84.0% vs. 95.7%, 0.0% vs. 38.2%, and 91.3% vs. 87.1%, respectively. The false-positive rate was 100% in group A and 61.8% in group B (p = 0.011).

CONCLUSIONS: A nodal diagnosis by CT is unreliable for patients who need additional gastrectomy after ESD.